Pliquett F, Pliquett U
Institute of Biophysics and Medical Physics, University of Leipzig, Germany.
Biophys Chem. 1996 Jan 16;58(1-2):205-10. doi: 10.1016/0301-4622(95)00099-2.
The passive electrical properties of human skin after separation from the body are predominated by the stratum corneum. Skin within a bath medium (150 mM phosphate buffered saline) at constant temperature (37 degrees C) exhibits a characteristic change of the passive electrical properties with time. Independent of the time the locus in the Z-plane is a depressed semicircular arc. The angle between the lines from the center of the arc to the points where the locus reaches the real axis remains unchanged. The difference between the high and low frequency resistivity (R0-Rx) increases over 10 h, reaches a plateau and decays after 20 h exponentially with a time constant of about 40 h. As model for the impedance we used a 5 element electrical circuit (R0, R1, R2, C1, C2), describing 3 pathways, (0) the dc path (appendages; R0), (1) tortuous pathways around the cell structures (R1, C1) and (2) direct pathways involving the corneocytes (R2, C2). There are characteristic changes with time in the elements of the equivalent circuit up to about 200 h after excision. Dramatic changes in C1 and R2 at about this time after separation strongly suggests destruction of the lipid structures. It will be suggested that the use of separated human stratum corneum as model for in vivo yields unreliable results after this time.
人体皮肤离体后的被动电学特性主要由角质层决定。置于恒温（37摄氏度）的浴液介质（150 mM磷酸盐缓冲盐水）中的皮肤，其被动电学特性会随时间呈现出特征性变化。在Z平面上，无论时间如何，轨迹都是一个凹陷的半圆弧。从圆弧中心到轨迹与实轴交点的连线之间的夹角保持不变。高低频电阻率之差（R0 - Rx）在10小时内增加，达到一个平稳期，20小时后呈指数衰减，时间常数约为40小时。作为阻抗模型，我们使用了一个五元件电路（R0、R1、R2、C1、C2），描述了三条路径，（0）直流路径（附属器；R0），（1）围绕细胞结构的曲折路径（R1、C1），以及（2）涉及角质形成细胞的直接路径（R2、C2）。在切除后长达约200小时的时间里，等效电路元件随时间有特征性变化。分离后大约在这个时间，C1和R2发生显著变化，强烈表明脂质结构遭到破坏。有人会提出，在这个时间之后，使用分离的人体角质层作为体内模型会得出不可靠的结果。
